1. Field of the Invention
The general inventive concept relates to a hard disk drive (HDD), and more particularly, to an HDD which can prevent or substantially reduce track non-uniformity generated when an interval between tracks is not maintained constant during copying of a servo pattern or recording of data due to an air force which concentrates on a head stack assembly (HSA), and further improve an overall quality and yield of the HDD.
2. Description of the Related Art
HDDs are data storage devices capable of recording data on a disk or reproducing data stored on the disk by using a read/write head. The HDDs are widely used as auxiliary memory devices of computer systems because of their relatively fast access time to a large amount of data for recording or reproduction.
As the HDD having a high tracks per inch (TPI) and a high bits per inch (BPI) can be embodied, an increase in a data storage capacity and a decrease in a size have been rapidly realized. Also, the application of the HDD has been expanded to laptops, MP3 players, mobile communication terminals, etc. Accordingly, there has been a request for development of a compact HDD which can be used for portable electronic products such as notebooks, personal digital assistants (PDAs), and mobile phones. Actually, an HDD having a diameter of 2.5 inches has been already developed and applied for notebooks. Also, a smaller HDD having a diameter of 0.8 inches, which has a size similar to a coin, has been recently developed and is already used or expected to be used for mobile phones or MP3 players.
Recently, as the high TPI is realized, track non-uniformity, which is caused when desired information is not properly recorded because an interval between tracks is not maintained constant during recording of the information on a track, is often generated. There may be various reasons for the track non-uniformity, for example, low stiffness of a spindle motor. In particular, there has been a study showing that the track non-uniformity is generated because an air force or an external interference, which is generated during a rotation of a disk, is concentrated on a head stack assembly (HSA) that reads or writes data by using a magnetic head mounted on an end portion of the HSA.
In a conventional HDD, for example, a shroud is installed on a base at an outside portion of a disk to reduce vibrations of the disk. The shroud often protrudes a predetermined height in an arc shape by contacting a side surface of the base. However, in the conventional HDD, due to the shroud being separately installed to reduce the vibration of a disk, the air force is concentrated on a spot, for example, the HSA. Accordingly, the track non-uniformity is generated which causes data to be inappropriately recorded on a track.
In particular, the air force that concentrates on the HSA acts as an obstacle not only to reading and recording of data as the TPI increases, but also to copying of a servo pattern in a process. Thus, an overall quality and yield of the HDD is deteriorated by the concentrated air force. Furthermore, there has been suggested an HDD without having a shroud. However, even when the shroud is removed, the vibration of a disk still remains unsolved.